Generation VI

Keen Eye now also ignores any increases in its target's evasion stages.

Outside of battle

From Pokémon Emerald onward, if a Pokémon with Keen Eye is in the first place in the party (even if fainted), there is a 50% chance that a Pokémon that would be encountered will not appear if its level would be 5 levels or more below the leading Pokémon's. It shares this effect with Intimidate.